To colour print your digital files, you need to provide the graphics and images in the optimum colour mode. Most of the software programmes allow you to work on RGB colour or CMYK colour. RGB colours or Red-Green-Blue colours are known as the primary colours of the light. This combination can be seen on your t.v. or computer monitors. Digital cameras and scanners also produce images with Red-Green-Blue colour combinations. Red-Green-Blue colour mode ought to be in use when taking photos that have to be seen on the monitor, emails or CD.
All the colours of the light spectrum are created from the primary colours, but monitors can display only a limited colour range from the visible spectrum. Light is sent from the monitors, and the ink recognizes only a certain wavelength of colours. The three primary colours are combined to create white. If the three primary colours are absent, then the light will show as black. By combining a variety of intensities of RGB colours, each combination produces different colours. The monitor of a television or a computer is made of small units known as pixels. Each pixel contains three units of light, and each unit represents red, green and blue.
You can not see the individual pixels with the naked eye as they are so tiny. Each pixel is made by the application of proper values of RGB, as without the proper values of the colour units, you cannot see any image on the screen. The values of RGB colours are calculated mainly by three methods. The first method is to set them with the help of different numeric values. The numeric values used for this purpose are the values from 0 to 255, and this is the superior method of the three.
The second method is by using hexadecimal notations. This method is mainly used for HTML and other languages of the computer. These notations follow a logical pattern. The hexadecimal notation consists of six characters, and these characters are divided into three. The first pair represents the red, the second pair green and the third pair as blue. Each pair is represented by a hexadecimal number (0-9) and the letters (A-F). The third method is the percentage in which a certain percentage represents each colour. The program translates these percentages into suitable values ranges from 0-255.
CMYK colours or Cyan-Magenta-Yellow colours are subtractive colours, whereas RGB colours are additive colours. Additive colours are referring to light, whereas subtractive colours refer to inks, paint or pigment. CMYK mode is used for printing as all kind of printers use subtractive colours to result in differing colours. When three additive colours are combined, the combination will produce white colour. But when three subtractive colours are combined, the combination produces black. This difference results in a great diversity between the resulting print and the onscreen display. Additive colour projects the light from the monitor, and if more light is projected from an independent pixel, it will be closer to the pure light. Regarding printer inks, they will absorb light and reflects only the wavelengths of light that is linked with the colour of the ink.
The inks of the printer are subtracting the non-essential wavelengths from the light that falls on the ink. The remaining light will return to the eye, resulting in the impression of a variety of colours. If you are mixing several colours, then more light will be absorbed by the ink and a lesser amount of light will be reflected to the eye, which results in darker colour. Black ink produced by the CMYK colours is not a strong black. You have to add black ink to produce the best results for printing true black. To get a darker variety of a colour, you have to add black in CMYK mode.
And how about the lighter shade of colours? Because white ink cannot be created using CMYK colours, you need to work under the hypothesis that you are printing the colours on a white paper. Because small dots of ink are used to print images the inks are used in a lower percentage to produce lighter shades so that more white colour is seen among the dots. The values of CMYK colours are calculated using four different percentages. The values of each percentage should be between 0 and 100 so that the total percentage of the ink values can be up to 400%. But when the total percentage reaches 400%, the ink will take more time to dry. Hence, the total percentage of the ink should not be more than 300% in CMYK mode.
Both colour modes have limitations. The images created using RGB mode can’t be converted smoothly into CMYK mode because of the brightness of RGB colours. Similarly, CMYK colours can’t be converted into RGB mode because the sharp look of RGB colours is missing in CMYK mode online. This is the reason why RGB colours are used in monitors and CMYK colours are used in printers.